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Патент USA US3059013

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3,059,03
s
Patented Oct. 16, 1962
1
2
tests the minimum initial charge necessary to give an
3,059,003
acid value of at least 180 for a given material at a given
MANUFACTURE OF POLYMERIC ACIDS
temperature can be determined. Thus, for example, if
Richard Rowe, Altrincham, England, assignor to Victor
the polymerisation is carried out at 300° C. and the
Wolf Limited, Manchester, England, a British com
pressure vessel is ?lled at room temperature to about 60%
Pan)’
of its capacity, this gives rise to a pressure of about 30
No Drawing. Filed Jan. 20, 1959, Ser. No. 787,809
to 75 p.s.i., according to the raw material to be poly
Claims priority, application Great Britain Jan. 21, 1958
men'sed.
9 Claims. (Cl. 260-407)
It has been found that in an autoclave ?lled with raw
The present invention concerns improvements in or re 10 material as usually as much as possible to its maximum
capacity, pressures are generated which, under the high
lating to the manufacture of polymeric acids. More
polymerisation temperatures, suffice to secure acid values
particularly, it relates to the polymerisation of polyun
of at least 180.
saturated fatty acids which at least partly consist of acids
In the experiment, the results of which are summarised
with conjugated double bonds to yield products consisting
predominately of dimeric acids.
15 in Table I below, dehydrated castor oil fatty acids of
about 50% conjugation were heated in an autoclave to
It is known to make dimeric acids by heat-polymerisa~
the polymerisation temperature for a given time. The
tion of polyunsaturated fatty acids but the products ob
autoclave was filled to 60% of its capacity. Afterwards
tained consist mainly of a mixture of dimeric and tri
the polymerisate was distilled in a vacuum of 2 milli
meric acids, together with unpolymerised monomeric acids.
If it is desired to obtain a product consisting mainly of .20 meters of mercury until the still temperature reached
285° C. The yield, as shown in Table I, was calculated
as a percentage of the raw material used and the viscosity
of the residue was determined at 25° C. Since the vis
cosity increases parallel with the trimer content of the
dimeric acids, then clearly it is necessary to choose con
ditions which prevent the formation of trimeric acids as
much as possible. This problem is particularly important
in the polymerisation of polyunsaturated fatty acids which
consist, at least partly, of acids with conjugated double 25 products, provided the removal of the monomeric acids
has always ‘been done under strictly identical conditions,
bonds, such as dehydrated castor oil fatty acids or isom
the viscosity ?gures give a fair indication of the tr-imeric
erised soya bean oil fatty acids, or other isomerised
acid content of the polymerised fatty acid.
fatty acids with a high linoleic acid content, such as
tall oil fatty acids or sa?lower oil fatty acids because in
this case there is a pronounced tendency for formation 30
Table I
of trimeric acids to prevail.
It has now been found it is not only possible to polym
erise polyunsaturated fatty acids to give products con
taining only moderate amounts of tlimeric acids, but also
at the same time to achieve better yields than those ob
35
Polymeric Acids
Amount
of raw
Temp.
Exp.
material,
(° 0.) (Hours)
'
parts
Time
Yield
Viscosity
(percent
inStokes
of raw
at 25° C.
tained by the known process.
material)
According to the present invention there is provided a
process for the heat-polymerisation under pressure of
100
300
3
54. 2
134. 9
polyunsaturated. fatty acids having a chain length corre
II
100 (
3
69.4
171.3
1
1
sponding to the natural fat acids and which at least partly 40 n1_____________ __
100 (2)325
2 }
68.4
159.1
consist of acids with conjugated double bonds in which
the polymerisation is effected in a plurality of stages and
The dehydrated castor oil fatty acids were then treated
in which, after each stage, the unpolymerised acids are
by the process of the invention in which they were heated
recovered by vacuum distillation, the next stage of the
polymerisation being carried out on the distillate.
45 to 300° C. for 11/2 hours whereafter the monomeric acids
were removed by ‘distillation. The distillate was polym~
Whilst the polymerisation process may be divided into
any number of stages it is preferable to use a two-stage
erised once more at 300° C. for 11/2 hours and freed
from monomeric acids as described above. The distillate
was subjected to a third polymerisation at 300° C. for
tinued when only a portion of the raw material, e.g. one
third or half, has been polymerised. Each polymerisa 50 11/2 hours and the reaction mixture worked up as de
tion stage may be carried out under more severe condi
scribed. The results obtained are summarised in the
process. In the ?rst stage the polymerisation is discon
following Table II:
tions of time and/or temperature than the immediately
preceding stage, especially if very mild conditions are
used in the ?rst stage. In the ?nal stage the conditions
must be severe enough to give a satisfactory overall yield, 55
Table II
but not too severe so as to endanger the quality of the
Polymeric Acids
product.
It has been found that very little decarboxylation occurs
if polyunsaturated fatty acids of the above type are heat
polymerised in a pressure vessel. The pressure required 60
is relatively low, e.g. 65 psi at 300° C. will give a prod
uct having an acid value of at least 180.
Amount of
Stage
Material, Yield (per
parts
cent dehydrated
Acid
Value
castor oil
Viscosity
in Stokes
at 25° 0.
fatty acids)
The pressure
may be‘ generated quite simply by means of the heat
expansion of the acid used as raw material, and this is
the preferred method of the invention. It is found that
300
156
105
48
16.8 74. 3
9. 5
185.3
95. 7
the acid value of the product depends, apart from the
polymerisation temperature, on the ratio of the amount of
In another process according to the invention only two
stages Were used. In stage I the polymerisation was
‘That is to say, the more material charged to the auto
carried out at 300° C. for one hour, in stage 11 (using the
clave, i.e. the higher the pressure, the nearer the acid 70 distillate of the polymerisate of stage 1 as raw material)
value of the polymeric acid approaches 190, which is
at 325° C. for 2 hours, with the results summarised in the
known as the practical limit. By means of preliminary
following Table III.
the initial charge to the capacity of the pressure vessel.
_ 3,059,003
4
to dimeric acids, removing the remainder of the non
Table III
polymerized fatty acids, and subjecting said remainder to
the aforesaid stage.
Polymeric Acids
Amount of
Stage
Material, Yield (per
parts
cent dehydrated
Acid
Value
castor oil
7
2. The process as de?ned in claim 1 wherein the pres
sure is from about 30 to 75 p.s.i.
3. The process as de?ned in claim 1 wherein the pres
Viscosity
in Stokes
sure is 65 p.s.i.
at 25° 0.
’
'
-
4. The process as de?ned in claim 1 wherein the por
fatty acids)
tion of the polyunsaturated fatty acids which is polym
I ___________________ __
100
H __________________ __
67
33
40} 73
. 185.7
105. 4
10 erized at each stage to dimeric acids is from about one
third to one-half of said fatty acids.
5. The process as de?ned in claim 1 wherein said re
If the acid obtained by caustic alkali treatment of soya
bean oil fatty acids (at 180° C.) was heated to 325° C. for
three hours in an autoclave ?lled to 55 w./v. percent of its
moving of the remainder of the non-polymerized fatty
capacity, subsequently removing the monomeric acids by
value of the resulting products is at least "180.
vacuum distillation, the distillation residue amounted to
41.2% of the isomerised acid which has a very high vis
cosity (164.9 stokes at 25° C.) and an acid value of 183.5.
The isomerised acid was then treated by the process of
the invention in which it was heated to 310° C. for one
hour in an autoclave ?lled to 65 w./v. percent of its capac
ity. V Afterwards, the non-polymerised acids, which were
removed by distillation from the dimeric acids, were once
acids is a vacuum distillation.
6. The process as de?ned in claim 1 wherein the acid
7. The process as de?ned in claim 1 wherein said
7 polyunsaturated fatty acids are selected from the group
consisting of dehydrated castor oil fatty acids, isomerised
soya bean oil fatty acids, tall oil fatty acids and sa?iower
oil fatty acids.
8. A process for forming products consisting predomi
nantly of dimeric acids from polyunsaturated fatty acids
having a chain length corresponding to the natural fat
.more polymerised at 330° C. for two hours in an auto
25 acids and which at least partly consist of acids with con
clave ?lled to 55 w./v. percent of its capacity. The mono
jugated double bonds comprising subjecting said polyun
meric acids were distilled OE and thus dimeric acids were
saturated fatty acids to a series of at least two stages, each
‘obtained. The total yield of dimeric acids amounted to
stage comprising heating said polyunsaturated fatty acids
49.3%. The viscosity of this product is only 104 stokes
under pressure resulting from the heating of said fatty
at 25° C. and the acid value 181.2.
Thus by the use of the process of the present invention
acids at a temperature of about 300° C. for a period of
‘products can be obtained which, by comparison with
about one hour, removing the remaining non-polymerized
fatty acids by vacuum distillation, and repeating said stage
products obtained by known processes have a lower tri
with the distillate at a temperature of about 325° C. for
meric acid content and witha higher yield. A high yield
a period of about two hours.
is normally associated with a high trimeric acid content. 35
9. The process as de?ned in claim 1 wherein said poly
I claim:
'
>
1. A process for forming products consisting predomi
nantly of dimeric acids from polyunsaturated fatty acids
unsaturated fatty acids are selected from the group con
sisting of dehydrated castor oil fatty acids, isomerised soya
bean oil'fatty acids, tall oil fatty acids and saf?ower oil
fatty acids, and repeating said stage with the distillate
7 having a chain‘ length corresponding to the natural fat
acids and which at least partly consist of acids with con
under more severe reaction conditions sufficient to give a
jugated double bonds comprising subjecting said polyun
satisfactory over-all yield but insufficient to endanger the
saturated fatty acids to a series of at least two stages
including a last stage, each stage comprising heating at a
temperature of about 280° C. to about 360° C. s'aid’poly
unsaturated fatty acids under pressure resulting from said 45
heating at a polymerization temperature for said fatty
acids for a period of time ranging from about 1 to 3
hours su?icient to polymerize a portion of said fatty acids
quality of the dimeric acid products.
.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,065,728
2,166,539
Oosterhof et a1 _________ __ Dec. 29, 1936
Briscoe ______________ __ July 18, 1939
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